Abstract

We demonstrate a dual-wavelength band optical frequency domain imaging (OFDI) system that provides high-resolution spectroscopic imaging with metallic nanoparticles as exogenous contrast agents. The local increase of the OFDI signal by elastic scattering from two different custom-fabricated nonspherical nanoparticles resonant at each wavelength band of the system was successfully detected, and we were able to distinguish and visualize the location of each of the nanoparticles in a scattering sample and in biological tissue.

Normalized extinction spectra of the gold nanorods (GNR) and the silver nanoplates (SNP) measured by a UV–Vis spectrometer. The gold nanorods and silver nanoplates were designed to have plasmon resonance at 1.0 and 1.3 μm, respectively.

Images of the nanoparticle solutions injected inside (a) two adjacent tubes and (b) gaps between scattering phantom and slightly inclined coverslips. The intensity images were normalized and median-filtered. For each set of images, (upper left) intensity image acquired with the 1.3 μm source, (lower left) intensity image acquired with the 1.0 μm source, (upper right) spectroscopic contrast image obtained by subtracting two intensity images, and (lower right) thresholded contrast superposed with the intensity image. The 1.3 μm resonant SNP is in the left tube (wedge) and the 1.0 μm resonant GNR is in the right tube (wedge). Scale bar: 100 μm.